Introduction: Within an International Atomic Energy Agency (IAEA) co-ordinated research project (CRP), a remote end-to-end dosimetric quality audit for intensity modulated radiation therapy (IMRT)/ volumetric arc therapy (VMAT) was developed to verify the radiotherapy chain including imaging, treatment planning and dose delivery. The methodology as well as the results obtained in a multicentre pilot study and national trial runs conducted in close cooperation with dosimetry audit networks (DANs) of IAEA Member States are presented.Material and methods: A solid polystyrene phantom containing a dosimetry insert with an irregular solid water planning target volume (PTV) and organ at risk (OAR) was designed for this audit. The insert can be preloaded with radiochromic film and four thermoluminescent dosimeters (TLDs). For the audit, radiotherapy centres were asked to scan the phantom, contour the structures, create an IMRT/VMAT treatment plan and irradiate the phantom. The dose prescription was to deliver 4 Gy to the PTV in two fractions and to limit the OAR dose to a maximum of 2.8 Gy. The TLD measured doses and film measured dose distributions were compared with the TPS calculations.Results: Sixteen hospitals from 13 countries and 64 hospitals from 6 countries participated in the multicenter pilot study and in the national runs, respectively. The TLD results for the PTV were all within ±5% acceptance limit for the multicentre pilot study, whereas for national runs, 17 participants failed to meet this criterion. All measured doses in the OAR were below the treatment planning constraint. The film analysis identified seven plans in national runs below the 90% passing rate gamma criteria.Conclusion: The results proved that the methodology of the IMRT/VMAT dosimetric end-to-end audit was feasible for its intended purpose, i.e., the phantom design and materials were suitable; the phantom was easy to use and it was robust enough for shipment. Most importantly the audit methodology was capable of identifying suboptimal IMRT/VMAT delivery.
- MeSH
- celková dávka radioterapie MeSH
- fantomy radiodiagnostické * MeSH
- jaderná energie MeSH
- kritické orgány * MeSH
- lidé MeSH
- mezinárodní agentury MeSH
- pilotní projekty MeSH
- plánování radioterapie pomocí počítače metody MeSH
- počítačová rentgenová tomografie MeSH
- radiometrie metody normy MeSH
- radioterapie s modulovanou intenzitou metody normy MeSH
- revize kvality lékařské péče metody normy MeSH
- studie proveditelnosti MeSH
- zajištění kvality zdravotní péče MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
Comparisons of national standard of air kerma for conventional and mammographic diagnostic X-ray radiation qualities were conducted by the IAEA. Eleven secondary standards dosimetry laboratories provided calibration data for Exradin A3 and Radcal RC6M transfer ionization chambers circulated. Each comparison result expressed as the ratio of the participant and IAEA calibration coefficient were within the acceptance limit of ±2.5%. From the 67 results of 11 participants and 10 available beam qualities, the comparison result was within its standard uncertainty in 63 cases, and within the expanded (k = 2) uncertainty in four cases. Detailed calibration uncertainty budgets from participant laboratories are presented. The relative standard calibration uncertainty of each participant was in the range of 0.5-1.3%. These results indicate that the calibration related uncertainty component is reasonable low for a clinical measurement. In addition to the calibration coefficient, other corrections should be applied for clinical measurement to achieve the recommended accuracy.
- MeSH
- mezinárodní agentury * MeSH
- radiometrie přístrojové vybavení normy MeSH
- referenční standardy MeSH
- vzduch * MeSH
- Publikační typ
- časopisecké články MeSH
UNLABELLED: The International Atomic Energy Agency (IAEA) has a long tradition of supporting development of methodologies for national networks providing quality audits in radiotherapy. A series of co-ordinated research projects (CRPs) has been conducted by the IAEA since 1995 assisting national external audit groups developing national audit programs. The CRP 'Development of Quality Audits for Radiotherapy Dosimetry for Complex Treatment Techniques' was conducted in 2009-2012 as an extension of previously developed audit programs. MATERIAL AND METHODS: The CRP work described in this paper focused on developing and testing two steps of dosimetry audit: verification of heterogeneity corrections, and treatment planning system (TPS) modeling of small MLC fields, which are important for the initial stages of complex radiation treatments, such as IMRT. The project involved development of a new solid slab phantom with heterogeneities containing special measurement inserts for thermoluminescent dosimeters (TLD) and radiochromic films. The phantom and the audit methodology has been developed at the IAEA and tested in multi-center studies involving the CRP participants. RESULTS: The results of multi-center testing of methodology for two steps of dosimetry audit show that the design of audit procedures is adequate and the methodology is feasible for meeting the audit objectives. A total of 97% TLD results in heterogeneity situations obtained in the study were within 3% and all results within 5% agreement with the TPS predicted doses. In contrast, only 64% small beam profiles were within 3 mm agreement between the TPS calculated and film measured doses. Film dosimetry results have highlighted some limitations in TPS modeling of small beam profiles in the direction of MLC leave movements. DISCUSSION: Through multi-center testing, any challenges or difficulties in the proposed audit methodology were identified, and the methodology improved. Using the experience of these studies, the participants could incorporate the auditing procedures in their national programs.
- MeSH
- dozimetry MeSH
- fantomy radiodiagnostické MeSH
- lidé MeSH
- mezinárodní agentury MeSH
- plánování radioterapie pomocí počítače metody normy MeSH
- radiometrie přístrojové vybavení metody normy MeSH
- řízení kvality MeSH
- termoluminiscenční dozimetrie přístrojové vybavení metody normy MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- Klíčová slova
- pH detekční metody, histochemické metody,
- MeSH
- acetylcholinesterasa * farmakologie fyziologie nedostatek škodlivé účinky MeSH
- biosenzitivní techniky metody normy přístrojové vybavení MeSH
- butyrylcholinesterasa * farmakologie fyziologie nedostatek škodlivé účinky MeSH
- chemické techniky analytické * využití MeSH
- cholinesterasové inhibitory MeSH
- cholinesterasy farmakologie fyziologie MeSH
- imunohistochemie metody normy přístrojové vybavení MeSH
- kolorimetrie metody normy přístrojové vybavení trendy MeSH
- lidé MeSH
- radiometrie metody normy přístrojové vybavení využití MeSH
- spektrofotometrie metody normy přístrojové vybavení MeSH
- titrace metody normy přístrojové vybavení MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
PURPOSE: Absorbed dose calibration for gamma stereotactic radiosurgery is challenging due to the unique geometric conditions, dosimetry characteristics, and nonstandard field size of these devices. Members of the American Association of Physicists in Medicine (AAPM) Task Group 178 on Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance have participated in a round-robin exchange of calibrated measurement instrumentation and phantoms exploring two approved and two proposed calibration protocols or formalisms on ten gamma radiosurgery units. The objectives of this study were to benchmark and compare new formalisms to existing calibration methods, while maintaining traceability to U.S. primary dosimetry calibration laboratory standards. METHODS: Nine institutions made measurements using ten gamma stereotactic radiosurgery units in three different 160 mm diameter spherical phantoms [acrylonitrile butadiene styrene (ABS) plastic, Solid Water, and liquid water] and in air using a positioning jig. Two calibrated miniature ionization chambers and one calibrated electrometer were circulated for all measurements. Reference dose-rates at the phantom center were determined using the well-established AAPM TG-21 or TG-51 dose calibration protocols and using two proposed dose calibration protocols/formalisms: an in-air protocol and a formalism proposed by the International Atomic Energy Agency (IAEA) working group for small and nonstandard radiation fields. Each institution's results were normalized to the dose-rate determined at that institution using the TG-21 protocol in the ABS phantom. RESULTS: Percentages of dose-rates within 1.5% of the reference dose-rate (TG-21+ABS phantom) for the eight chamber-protocol-phantom combinations were the following: 88% for TG-21, 70% for TG-51, 93% for the new IAEA nonstandard-field formalism, and 65% for the new in-air protocol. Averages and standard deviations for dose-rates over all measurements relative to the TG-21+ABS dose-rate were 0.999±0.009 (TG-21), 0.991±0.013 (TG-51), 1.000±0.009 (IAEA), and 1.009±0.012 (in-air). There were no statistically significant differences (i.e., p>0.05) between the two ionization chambers for the TG-21 protocol applied to all dosimetry phantoms. The mean results using the TG-51 protocol were notably lower than those for the other dosimetry protocols, with a standard deviation 2-3 times larger. The in-air protocol was not statistically different from TG-21 for the A16 chamber in the liquid water or ABS phantoms (p=0.300 and p=0.135) but was statistically different from TG-21 for the PTW chamber in all phantoms (p=0.006 for Solid Water, 0.014 for liquid water, and 0.020 for ABS). Results of IAEA formalism were statistically different from TG-21 results only for the combination of the A16 chamber with the liquid water phantom (p=0.017). In the latter case, dose-rates measured with the two protocols differed by only 0.4%. For other phantom-ionization-chamber combinations, the new IAEA formalism was not statistically different from TG-21. CONCLUSIONS: Although further investigation is needed to validate the new protocols for other ionization chambers, these results can serve as a reference to quantitatively compare different calibration protocols and ionization chambers if a particular method is chosen by a professional society to serve as a standardized calibration protocol.
- MeSH
- celková dávka radioterapie MeSH
- fantomy radiodiagnostické MeSH
- kalibrace normy MeSH
- klinické protokoly normy MeSH
- radiochirurgie přístrojové vybavení metody normy MeSH
- radiometrie metody normy MeSH
- voda MeSH
- vzduch MeSH
- záření gama terapeutické užití MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Geografické názvy
- Spojené státy americké MeSH
- Klíčová slova
- volumetric modulated arc therapy, Octavius QA system,
- MeSH
- částice - urychlovače MeSH
- chyby nastavení radioterapie prevence a kontrola MeSH
- filmová dozimetrie přístrojové vybavení MeSH
- lidé MeSH
- nádory hlavy a krku radioterapie MeSH
- nádory prostaty radioterapie MeSH
- plánování radioterapie pomocí počítače * MeSH
- radiometrie normy přístrojové vybavení MeSH
- radioterapie s modulovanou intenzitou * metody normy přístrojové vybavení MeSH
- reprodukovatelnost výsledků MeSH
- řízení kvality * MeSH
- rotace MeSH
- záření gama MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- hodnotící studie MeSH
A simple hemispherical phantom has been designed and prepared for the EURADOS intercomparison exercise on (241)Am activity determination in the skull (2011-13). The phantom consists of three parts that substitute bone and soft tissues. (241)Am is deposited on the surfaces of the bone-substituting part. The design and assumed composition of phantom parts are discussed. A preparation of the voxel representation of the phantom is described. The spectrum of a real measurement of the physical phantom agrees well with the simulation. The physical phantom, and its voxel representation, is provided to the participants of the intercomparison exercise.
- MeSH
- americium analýza MeSH
- design vybavení MeSH
- fantomy radiodiagnostické MeSH
- fotony MeSH
- kalibrace MeSH
- kosti a kostní tkáň MeSH
- lebka účinky záření MeSH
- metoda Monte Carlo MeSH
- monitorování radiace metody MeSH
- počítačová rentgenová tomografie MeSH
- polyurethany chemie MeSH
- radiometrie metody normy MeSH
- reprodukovatelnost výsledků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
- MeSH
- anizotropie MeSH
- brachyterapie * metody přístrojové vybavení využití MeSH
- dávka záření MeSH
- fantomy radiodiagnostické využití MeSH
- fotony diagnostické užití terapeutické užití MeSH
- ionizující záření MeSH
- lidé MeSH
- metoda Monte Carlo * MeSH
- radiometrie metody normy využití MeSH
- rentgenové záření MeSH
- spektrální analýza metody využití MeSH
- statistika jako téma MeSH
- teoretické modely MeSH
- výzkumný projekt MeSH
- zařízení a zdroje radiace * trendy využití MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
A new triple-to-double coincidence ratio (TDCR) system has been established at CMI as an additional technique for primary activity standardisation. Details of the detectors and the electronics are given. Construction of the optical chamber was validated using measurement of a (3)H standard-the efficiency achieved with Ultima Gold was 58%. Several methods of efficiency variation (coloured bands painted on vial, positioning and photomultipliers defocussing) are compared. Activity concentrations of (204)Tl and (45)Ca were determined with the TDCR method and with the efficiency tracer technique. Advantages of the TDCR method compared to the efficiency tracing method and agreement between results are shown.
- MeSH
- analýza selhání vybavení MeSH
- dávka záření MeSH
- design vybavení MeSH
- internacionalita MeSH
- poločas MeSH
- radioizotopy thallia analýza normy MeSH
- radioizotopy vápníku analýza normy MeSH
- radiometrie přístrojové vybavení normy MeSH
- referenční hodnoty MeSH
- referenční standardy MeSH
- Publikační typ
- časopisecké články MeSH
In nuclear facilities stack monitors are used for the measurement of the volumetric activity of noble gases. Spectrometric measurement is needed because the content of stack effluents is always a mixture of radionuclides. In some nuclear power plants new types of monitors were installed based on HPGe detectors. For efficiency calibration a standard with the radionuclide Xe-127 was developed and calibration curve constructed in the energy range 81 keV-1293 keV. Experiental efficiencies were checked using an MC model.
- MeSH
- analýza selhání vybavení MeSH
- dávka záření MeSH
- design vybavení MeSH
- internacionalita MeSH
- jaderné elektrárny přístrojové vybavení normy MeSH
- kalibrace MeSH
- poločas MeSH
- radioaktivní látky znečišťující vzduch analýza MeSH
- radiometrie přístrojové vybavení normy MeSH
- referenční hodnoty MeSH
- referenční standardy MeSH
- vzácné plyny analýza MeSH
- Publikační typ
- časopisecké články MeSH
